Embodiments of the present invention relate generally to determination of arterial stiffness indicative of medical conditions, and more particularly to systems and methods for estimation of arterial pulse wave velocity based on a hemodynamic model.
Atherosclerosis is referred to narrowing and stiffening of blood artery associated with deposition of fat inside the arterial walls. Arterial stiffness provides an indication of a number of medical conditions such as diabetes and hypertension. Determination of arterial stiffness provides an indication of a medical condition and progression of disease. In some instances, treatment options may be determined based on the arterial stiffness.
When the heart beats, a pulse is transmitted through the arterial system. The pulse wave propagates through the arterial system by distending the elastic walls of the arteries. Arterial pulse velocity is mathematically similar to phase velocity of electrical waves propagating in a cable or transmission line. The arterial wave equation is characterized by compliance of the artery, inertia of blood, and blood viscous resistance which corresponds to capacitance, inductance and resistance of the electrical wave equation.
The arterial pulse wave velocity is used to determine the stiffness of the blood vessel. One technique of estimating the arterial pulse wave velocity from blood flow data is the foot-to-foot method. Such a technique involves tracking changes in blood flow as a function of time and position along the blood vessel, and then tracking motion of a fiduciary point in the blood flow waveform as the wave propagates along the length of the blood vessel. A pulse wave velocity is estimated based on time delay between fiduciary points at two locations along the length of the blood vessel and the distance between the two locations. However, the arterial pulse wave velocity estimated by such a technique can be affected by wave reflection and by choice of the fiduciary point.